1. Field
Embodiments of the invention relate to microphone devices and methods for packaging the same.
2. Description of the Related Technology
Generally, relatively small-sized acoustic transducer components are configured for surface mounting on a carrier board, such as a printed circuit board, to establish electrical contact between the acoustic transducer component and electronic circuitry disposed on the carrier board. The acoustic transducer component is provided with a sound port, typically in the form of a hole, for allowing passage of sound pressure between the exterior of the component and an acoustic transducer disposed inside the acoustic transducer component.
Conventionally, the sound port is provided either as a top-port or a bottom-port. In a top-port configuration, the transducer component or package has electrodes or solder-pads disposed on a bottom surface abutting the carrier board and the sound port is disposed on a top surface. Conversely, in a bottom-port configuration, the sound port is disposed on the bottom surface with the electrodes or solder-pads positioned around the sound port opening. Thus, a bottom-port package has the sound port on the same side as the package leads, whereas a top-port package has the sound port on a different, typically opposite, side from the package leads. The acoustic transducer component of a bottom-port design is typically mounted on a carrier board with a hole aligned with the sound port opening to allow passage of sound pressure between the exterior of the component and the acoustic transducer inside the acoustic transducer component.
Typically, microelectromechanical systems (MEMS) microphone devices are configured with a bottom-port to aid in providing a sufficiently large back volume behind a moveable member of the acoustic transducer. Condenser microphones or electret condenser microphones (ECMs) have a different construction and are typically configured with a top-port to allow a sufficiently large back volume.
The construction of the product using the acoustic transducer (e.g., a mobile phone) can dictate use of either the MEMS devices or the ECM devices, depending upon whether the mounting area is better suited to bottom-port or top-port mounting. However, since the two types of microphone devices have different properties and qualities, in certain implementations, such as those demanding a relatively high signal-to-noise ratio, it may not be desirable for the structure of the product incorporating the microphone package to dictate the type of the acoustic transducer.
Conventionally, an acoustic transducer component or package comprises an acoustic transducer and a housing that includes lid and a rigid substrate with first and second surfaces opposite each other. The housing has an exterior top surface, and the rigid substrate is disposed with its second surface as an exterior bottom surface of the housing. Electrical terminals are disposed on the second surface of the rigid substrate. The acoustic transducer component is also denoted a microphone package.
Examples of acoustic transducer components or packages are disclosed, e.g., in US Patent Publication No. 2010/0090295 and U.S. Pat. No. 7,202,552. There is a need for improved microphone packages, and methods of forming the same.